Viability Loss of Recalcitrant Brant’s Oak (Quercus brantii Lindl.) Acorns during Overwintering

The lack of germination success and subsequent seedling recruitment of recalcitrant acorns of Brant’s oak (Quercus brantii) has been described as one of the main reasons for the cessation of sexual regeneration in Zagros forests. What happens to acorns whose viability is immediately lost is examined in the form of overwintering. In this study, overwintering conditions following seed dispersal were simulated by subjecting freshly harvested acorns with three moisture content levels (85, 90 and 100% fully hydration) at 3°C for up to three months. The results indicated that Brant’s oak acorns are totally recalcitrant and show no signs of dormancy. Their viability depended entirely on the moisture content. Fully hydrated acorns maintained a viability rate of more than 80% after three months of overwintering. This time period for acorns with 95% full hydration lasted only one month. At 90% fully hydration, the viability rate of acorns decreased almost immediately to less than 80%, and to less than 50 and 20% after 1 and 3 months, respectively. The passage of time was deteriorating during overwintering and its negative effects accelerated after one month, even for fully hydrated acorns.